STABILITY OF COHERENTLY STRAINED SEMICONDUCTOR SUPERLATTICES

The excess energy of several III-V and II-VI strained-layer semiconductor superlattices (AC)p(BC)p is studied as a function of the repeat period p and orientation G=[001], [110], [111], and [201], using first-principles calculations. We discover a number of universal features, including the predicted instability for nearly all ps and Gs with respect to bulk disproportionation, the identification of chalcopyrite as a metastable ordered structure, and the stability of all thin epitaxial [110] and [201] and most common-anion [001] superlattices relative to coherent phase separation. © 1990 The American Physical Society.